In a process of weld inspection, we can relate them to sizes, dimensions, discontinuities, etc. The discontinuities in the welding refer to imperfections that exist within and/or adjacent to the welding. when you make one welding, the size is important, because that way we will know the resistance of its union and what it will entail later. make a welding inspection it is necessary to check the quality of the welded joint. One of the main reasons for inspection is when a joint is of the proper quality for a joint of welding.
This is the name given to the process that consists of verifying, examining and reporting on a welding job, based on the standards and codes that govern welding. These are criteria with which we work to examine the dimensions and discontinuities that every welded joint has. It is also important to talk about fabrication drawings and welding symbols. These charts show essential characteristics such as size, length, location based on numerous design calculations that meet the demands of a weld joint.
In an inspection process, the welding inspector You should initially know:
- Understanding weld drawings.
- Different designs of welded joints.
- Know the destructive and non-destructive tests that are used in welding.
- The development of welding procedures.
- Know and interpret welding symbols.
- Know and interpret the requirements of codes and standards used in welding.
A welding inspector You should know the following methods to develop before carrying out an inspection:
- Ultrasound Test (UT) Based on the transmission of sound waves through the material. It detects movements, vibrations that the human ear cannot perceive. These movements or vibrations are conducted through the material, and if the material is interrupted, refraction or distortion occurs. This interruption happens in a change of intensity, direction and angle of propagation. The UT then detects and records through a specialized monitor.
- Radiographic Test (RT) Used to indicate the penetration capacity as well as in X-Rays and Gamma Rays. Before some internal change within a material, we can determine with this test, measuring the incident radiation against the released radiation.
- Magnetic Particles (MT) It is a type of Non-Destructive test, based on the physical principle called Magnetism. Small pieces of Magnetic Particles are used, where the presence of discontinuities in the metal surface will be revealed.
- Penetrating Liquids (PT) Supported by the physical principle called «Capillarity», it consists in the application of a solution with good penetration characteristics. Then, an absorbent liquid is applied, called a developer, its color is different from the penetrating liquid, it will absorb the liquid that has penetrated, revealing the superficial cracks.
- Visual Inspection (VT)With this test, being the most used, we can obtain information about the surface condition of the inspected material.
The visual inspection will be carried out before, during and after welding.
1. Before the welding process
- Check the layout of the joint, its dimensions and the finish.
- Check clearance and dimensions of ring or backing plate.
- Check the alignment of the parts to be welded.
- Check cleanliness.
2. During the welding process
- Check the welding process at all times.
- Examine the preparation of the board.
- Monitor preheating and temperature between steps.
- Inspect for proper filler metal, flux, or shielding gas.
- Examine the distortion control.
3. After the welding process
- The inspector shall verify consistency with the requirements of the drawing.
- Approval by the inspector regarding the welds and their appearance.
- Check for excessive polishing, mishandling of the machine, or process damage.